Conventionally, in a work vehicle such as a tractor and a back hoe loader, a front work machine such as a loader is mounted on a front portion of a main machine (vehicle) thereof. Some of these front work machines are constituted such that a base portion(s) (rear end portions) is supported by one side or both right and left sides of a bonnet provided in the front portion of the main machine. That is, the constitution is such that on each of the right and left sides or one side of the bonnet, a turnably-supporting part made of a bracket or the like is provided in a body frame or the like on the main machine, and that the base portion of the front work machine is supported by this turnably-supporting part. This allows the front work machine to be supported so as to turn vertically with respect to the main machine (e.g., refer to Patent Document 1).
In the front work machines as described above, some are constituted so as to have a bucket constituted openably and closably by a hydraulic cylinder, a hydraulically-driven auger or the like as a work part, and to require hydraulic oil for operation. In such a constitution, hydraulic piping is extended from the main machine side, and the hydraulic oil is supplied through this hydraulic piping.
In this manner, when the hydraulic oil is supplied to the work part and the like of the front work machine by the hydraulic piping extended from the main machine side, the following problems arise due to the constitution of the front work machine.
As described before, in the case where the front work machine is constituted so as to be supported on the side(s) of the bonnet, the arrangement of the hydraulic piping between the bonnet and the front work machine requires sufficient space between the bonnet and the front work machine. Providing such space for piping causes an increase in total width of the front work machine, and thus, causes an increase in total width of the work vehicle including the main machine.
Moreover, since the front work machine turns vertically with respect to the main machine as described before, the hydraulic piping needs to follow the movement of the front work machine by this turning. That is, the front work machine is a moving side, while the main machine is a non-moving side, and thus, a necessary length of the hydraulic piping connecting the front work machine and the main machine may vary, and also, it can be considered that the turning of the front work machine puts a burden on the hydraulic piping, thereby decreasing its durability, which makes it necessary that the hydraulic piping follows the front work machine.
Consequently, there has been desired a piping structure of the front work machine which prevents an increase in total width of the front work machine due to the hydraulic piping extended from the main machine side, and enables the piping following the structure of the front work machine turning vertically, by which the burden on the hydraulic piping accompanying the turning of the front work machine can be decreased to increase the durability.
[Patent Document 1] Japanese Patent Application Laid-Open No. 2002-308157